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Published on: December 2, 2022
Amaranthus tricolor crude extract inhibits Cronobacter sakazakii isolated from powdered infant formula
Peng Fei1, Hongxia Feng2, Yanyan Wang3
1College of Food and Bioengineering, Henan University of Science and Technology, Luoyang, 471023, China.
Insights
Amaranthus tricolor crude extract (ATCE) effectively combats Cronobacter sakazakii in powdered infant formula. This natural disinfectant disrupts bacterial cell membranes and DNA, showing potential for food safety applications.
Area of Science:
- Food Microbiology
- Natural Product Chemistry
- Bacteriology
Background:
- Cronobacter sakazakii is a pathogen found in powdered infant formula (PIF).
- Contamination of PIF poses a significant risk to infant health.
- Natural antimicrobials are sought for food safety applications.
Purpose of the Study:
- To investigate the antibacterial activity of Amaranthus tricolor crude extract (ATCE) against Cronobacter sakazakii.
- To elucidate the mechanism of action of ATCE.
- To evaluate ATCE's efficacy in controlling Cronobacter sakazakii biofilms.
Main Methods:
- Antibacterial activity assessed via inhibition zone, MIC, and MBC.
- Mechanism of action studied through growth curves, cell membrane potential, intracellular pH, protein, DNA content, and morphology.
- Biofilm disinfection efficacy tested on stainless steel surfaces.
Main Results:
- ATCE demonstrated significant antibacterial activity with inhibition zones ranging from 14.35 to 14.84 mm.
- MIC and MBC values were determined as 20 mg/mL and 40 mg/mL, respectively.
- ATCE disrupted cell membranes, reduced intracellular pH, inhibited protein and DNA synthesis, and caused cell deformation, effectively inactivating biofilms.
Conclusions:
- Amaranthus tricolor crude extract exhibits potent antibacterial properties against Cronobacter sakazakii.
- ATCE acts by damaging bacterial cell membranes and interfering with essential cellular processes.
- ATCE shows promise as a natural disinfectant for reducing Cronobacter sakazakii contamination in powdered infant formula.
Abstract:
The purpose of this study was to elucidate the antibacterial activity and possible mechanism of action of Amaranthus tricolor crude extract (ATCE) against Cronobacter sakazakii isolated from powdered infant formula (PIF). The antibacterial activity of ATCE was assessed by measuring the diameter of inhibition zone (DIZ), minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). The possible mechanism of action of ATCE was revealed by analyzing the effects of ATCE on growth curves and changes in cell membrane potential, intracellular pH, content of bacterial protein and genomic DNA, and cell morphology. Finally, ATCE was applied to the disinfection of C. sakazakii in biofilm on stainless steel tube. The results showed that the DIZ, MIC, and MBC of ATCE against C. sakazakii strains were from 14.35 ± 0.67 to 14.84 ± 0.67 mm, 20 mg/mL, and 40 mg/mL, respectively. Treatment with ATCE ended the logarithmic growth phase of C. sakazakii, and led to depolarization of the cell membranes, reducing intracellular pH and bacterial protein and genomic DNA contents, and resulting in cytoplasmic leakage and deformation. In addition, ATCE effectively inactivated C. sakazakii in biofilm, reducing viable bacteria by approximately 6.5 log cfu/mL bacterial count after treatment with 1 MIC (1 MIC = 20 mg/mL) of ATCE for 20 min at 25°C. Our findings showed that ATCE inactivated C. sakazakii strains isolated from PIF and has potential as a natural disinfectant to reduce the contamination of PIF by C. sakazakii.
